Trace metals Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, and As were determined on a monthly basis in a total of 52 rain samples collected from six different locations in the central region of Mexico during March 2016–April 2017. The average concentrations of trace metals (mg/L) in the rainwater samples showed an order of Zn (0.873) > Fe (0.395) > Mn (0.083) > Cr (0.041) ≥ Cu (0.041) > Pb (0.031) > Ni (0.020) > Co (0.013) > As (0.0003) > Cd (0.002). The differences observed in metal concentrations are related to variations in the influence of continental air masses, local transport, regional advection, and the solubility of trace metals. High concentrations of metals were observed in the months of March to May at all sites, probably due to the less extensive removal of air/air pollutants. The values obtained from the enrichment factor (EF) per metal showed relatively high values for Cd, Zn, Cu, Pb, Co, Ni, and Cr, suggesting anthropogenic origin. Pearson’s correlation matrix validated the distribution of trace metal sources and their relationships with local/regional meteorological characteristics. This paper presents relevant basic information for the evaluation of the toxic potential of rainwater and the possible health risks when using this source of water for human consumption.

Six silvofishery systems were constructed to estimate the potential use of mangrove seedlings for nutrient removal. Two systems did not contain seedlings (i.e., control treatment), while the remaining systems were divided into separate treatments using two mangrove species (Laguncularia racemosa and Rhizophora mangle). Each system consisted of two water tanks linked by two hoses. The first tank contained 150 poeciliid fishes, while the second contained a biological filter of gravel and sand on the bottom, as well as a hydroponic arrangement of 34 seedlings. Water exchange between both tanks was performed over a 24-h period, every ten days for seven months, and the concentration of nutrients (NH4+, NO2–, NO3–, and PO4–3) was measured every 8 h. Laguncularia racemosa showed a higher growth rate compared to R. mangle, but there were no differences regarding the growth of fishes among the six systems. Final dissolved inorganic nitrogen removal was 42% in the control treatment and 90% in both treatments using mangroves. Dissolved inorganic phosphorus removal was 45% in the control treatment, 44% in the L. racemosa treatment, and 35% in the R. mangle treatment. Our results indicate that both mangrove species are capable of removing a considerable amount of nitrogen, but phosphorus removal was unsatisfactory.

El desequilibrio ambiental que fertilizantes químicos ocasionan en los suelos, y la necesidad de preservar la materia orgánica para la sostenibilidad y productividad de los sistemas agrícolas, ha propiciado retornar al uso de abonos orgánicos. El objetivo del presente estudio fue determinar las características fisicoquímicas y microbiológicas, como indicadores de calidad, en abonos orgánicos. El experimento se realizó en diseño de bloques al azar, cuatro repeticiones y siete tratamientos¸ T1: lixiviado de calcio, T2: extracto líquido de humus de Ca, T3: humus de plátano, T4: humus concentrado de Ca, T5: lombricomposta, T6: extracto líquido de lombricomposta y T7: abono de origen comercial (control). Los abonos lombricomposta, humus de plátano y comercial mostraron valores altos de nitrógeno y fosfato. Los abonos presentaron niveles de pH y conductividad eléctrica (CE) inferiores a los indicados en NOM‑021‑RECNAT-2000. El coeficiente de correlación fue positivo entre CE y nutrientes. El abono comercial presentó concentraciones elevadas en Cr y Pb, sin exceder los límites máximos permisibles por la NOM-052-SEMARNAT-2005. Como respuesta biológica, las semillas de lechuga y rábano presentaron el IG más bajo en humus de plátano, humus concentrado de calcio y abono comercial. Los análisis microbiológicos presentaron ausencia en el indicador de Salmonella spp. y resultados mayores al límite máximo permisible para uso en la agricultura en coliformes fecales y totales. Los abonos orgánicos son elaborados con residuos de origen vegetal, animal o ambos, algunos sin control adecuado, por lo que se convierten en un problema de contaminación. Debido a la creciente demanda de abonos orgánicos es importante su estudio, ya que no existe normatividad mexicana que defina normas técnicas que establezcan características de calidad en abonos orgánicos para uso en la agricultura. Las características fisicoquímicas y biológicas varían dependiendo del material utilizado en la elaboración, lo cual es un factor que debe considerarse para obtener un producto final que aporte nutrientes disponibles a las plantas.

Sinaloa State is the second largest producer of shrimp in Mexico, after Sonora, (in 2008 more than 35,000 tones, and 300 shrimp farms covering...